Plasticizers are incorporated into polymers to improve properties, such as, enhanced processibility and increased pliability at low temperature. Practicable plasticizers exhibit certain critical characteristics including chemical inertness toward the polymer, low volatility at the polymer fusion temperature, compatibility with the polymer the lack of which leads to exudation of the plasticizer and depending upon the intended use other characteristics such as light stability and solvent resistance. Thermoplastic copolyetherester elastomers exhibit such limited compatbility toward phthalate plasticizers that in order to incorporate significant amounts of plasticizer, the addition of a more compatible polymer such as vinyl chloride polymer is used. Moreover, because of the high melting point of certain copolyetherester. elastomers, the incorporation of plasticizers and vinyl chloride polymer is difficult because processing temperatures can exceed the decomposition temperature of the vinyl polymer. Further, at high processing temperature ester containing plasticizers tend to intercharge with the ester groups of the elastomers. Sulfonamide plasticizers are considered unsatisfactory for polyesters because of incompatibility when the amount of plasticizer exceeds 10 parts plasticizer or more per 100 parts polyester. Accordingly, it was unexpected to find that co-polyetherester elastomers are compatible with certain sulfonamides at high concentrations.